1. Plans for new LHC injectors R. Garoby
Linac4 Advisory Committee – 29 January 2008
Plans for new LHC injectors R. Garoby
Content
Introduction: new activities
Scenarios for the upgrade of the accelerators
Linac4 / SPL / PS2
Roadmap
Conclusion

2. New Activities 2008-2011 (1/2) Quote from R. Aymar (16 January 2008)

3. New Activities 2008-2011 (2/2) Quote from R. Aymar (16 January 2008)

4. UPGRADE SCENARIOS FOR THE ACCELERATORS
29 January 2007

5. Today’s performance for LHC
Maximum energy
Required intensity/bunch (at high energy)
Obtained intensity/bunch (at ejection)
Limitations*
Linac2
50 MeV
Too low energy
PSB
1.4 GeV
~ ultimate beam
Too low injection energy (space charge) PS
25 GeV
p/b
(~ 90 % of ultimate beam)
Transition / Impedance ?
Poor longitudinal match with SPS
Reliability (age)
SPS
450 GeV
p/b
(nominal beam)
Too low injection energy
e-cloud
Impedance
LHC
Nominal
Ultimate
1.15 × 1011 p/b
1.70 × 1011 p/b
???
Too low injection energy (DA, Snap-back) ?
e-cloud ?
Unexpected beam loss: > 10 %
Conclusion – OK for the first phase of operation of LHC, but:
bottleneck for reaching “ultimate” characteristics
major risk of poor reliability due to age and performance stretch
29 January 2007

6. Needs of SLHC Two new upgrade scenarios (LUMI’06) (from F. Zimmermann)
parameter
symbol
25 ns, small b*
50 ns, long
transverse emittance
e [mm]
3.75
protons per bunch
Nb [1011]
1.7
4.9
bunch spacing
Dt [ns] 25 50
beam current
I [A]
0.86
1.22
longitudinal profile
Gauss
Flat
rms bunch length
sz [cm]
7.55
11.8
beta* at IP1&5
b* [m]
0.08
0.25
full crossing angle
qc [mrad]
381
Piwinski parameter
f=qcsz/(2*sx*)
2.0
hourglass reduction
0.99
peak luminosity
L [1034 cm-2s-1]
15.5
10.7
peak events per crossing
294
403
initial lumi lifetime
tL [h]
2.2
4.5
effective luminosity
(Tturnaround=10 h)
Leff [1034 cm-2s-1]
2.4
2.5
Trun,opt [h]
6.6
9.5
(Tturnaround=5 h)
3.6
3.5
4.6
6.7
e-c heat SEY=1.4(1.3)
P [W/m]
1.04 (0.59)
0.36 (0.1)
SR heat load K
PSR [W/m]
0.36
image current heat
PIC [W/m]
0.33
0.78
gas-s. 100 h (10 h) tb
Pgas [W/m]
0.06 (0.56)
0.09 (0.9)
extent luminous region
sl [cm]
3.7
5.3
comment
D0 + crab (+ Q0)
wire comp.
Two new
upgrade
scenarios (LUMI’06)
Compromises
between
heat load
and # pile up
events
29 January 2007

7. Upgrade procedure 1. Lack of reliability:
Ageing accelerators (PS is 48 years old !) operating far beyond initial parameters
Þ need for new accelerators designed for the needs of SLHC
2. Main performance limitation:
Excessive incoherent space charge
tune spreads DQSC at injection in the
PSB (50 MeV) and PS (1.4 GeV) because
of the high required beam brightness N/e*.
Þ need to increase the injection energy in the synchrotrons
Increase injection energy in the PSB from 50 to 160 MeV kinetic
Increase injection energy in the PSB from 25 to 50 GeV kinetic
Design the PS successor (PS2) with an acceptable space charge effect for the maximum beam envisaged for SLHC: => injection energy of 4 GeV
29 January2007

8. Updated list of future accelerators
Present accelerators
Future accelerators
Linac2
Linac4
50 MeV
160 MeV
(LP)SPL is the baseline injector for PS2
PS2 size is 15/77 of SPS
PSB
(LP)SPL
1.4 GeV
4 GeV PS
26 GeV
PS2
50 GeV
(LP)SPL: (Low Power) Superconducting Proton Linac (4-5 GeV)
PS2: High Energy PS
(~ 5 to 50 GeV – 0.3 Hz)
SPS+: Superconducting SPS
(50 to1000 GeV)
SLHC: “Superluminosity” LHC
(up to 1035 cm-2s-1)
DLHC: “Double energy” LHC
(1 to ~14 TeV)
Output energy
SPS
450 GeV
SPS+
1 TeV
LHC /
SLHC
DLHC
7 TeV
~ 14 TeV
29 January 2008

9. Expected benefits of the successive stages of upgrade for the LHC1 2 3
DESCRIPTION (new accelerator)
Linac4
PSB PS
SPS
(LP)SPL
PS2
SPS+
Characteristics of beam entering PS/PS2
~ Ultimate LHC beam in 1 PSB pulse instead of 2
>> Ultimate LHC beam in 2 PSB pulses
>2x ultimate LHC beam in 1 injection
- As in stage 3
Characteristics of beam entering SPS/SPS+
- 72 ultimate LHC bunches every 2.4s (instead of 3.6s)
- Higher reliability (no long flat porch at PS injection)
- Reduced injection flat porch
(7.2s instead of 10.8s)
- Possibility to study SPS limitation with brightness beyond ultimate
Energy x2 (~50GeV) => improved SPS behaviour (farther from transition, reduced space-charge etc.)
- Reduced injection flat porch (2.4s instead of 10.8s)
- Highest reliability (no PS)
- Capability to push the SPS to its maximum potential
Characteristics of beam entering LHC
- Capable of beam luminosity above nominal
(³ 1034 cm-2s-1)
- Higher reliability
- Reduced filling time
- Beam characteristics for LHC luminosity upgrade
(>> cm-2s-1)
- Highest reliability
- Minimum filling time +
- Energy x2 (~1 TeV)
- Capability to push the LHC to its maximum potential
- Adequate for DLHC
29 January 2008

10. DESCRIPTION (new accelerator)
Expected benefits of the successive stages of upgrade for other CERN users
STAGE 1 2 3
DESCRIPTION (new accelerator)
Linac4
PSB PS
SPS
(LP)SPL
PS2
SPL
b beam -
++ (g ~100)
n Factory
+++ (~5 GeV prod. beam)
k, m
~400 kW beam at
50 GeV
ISOLDE
~double intensity
~ n times intensity
EURISOL
+++
29 January 2008

11. Layout of the new accelerators (1/2)
SPL service building s
PS2
(LP)SPL
Linac4 will be built at its “final” location
Linac4
29 January 2008

12. Layout of the new accelerators (2/2)
29 January 2008

13. Linac4: main characteristics
Ion species H-
Output energy
160 MeV
Bunch frequency
352.2 MHz
Max. repetition rate
2 Hz
Beam pulse duration
0.4 ms
Chopping factor (beam on)
62%
Source current
80 mA
RFQ output current
70 mA
Linac current
64 mA
Average current during beam pulse
40 mA
Beam power
5.1 kW
Particles p. pulse
Transverse emittance (source)
0.2 mm mrad
Transverse emittance (linac)
0.4 mm mrad
29 January 2008

14. Linac4 building and infrastructure
29 January 2008

15. (LP)SPL: main characteristics
Stage 2 2’
CDR2
“LPSPL” for SPS & LHC
“SPL”
Energy (GeV)
3.5 4 5
Beam power (MW)
0.19
4 - 8
Rep. frequency (Hz) 50
Protons/pulse (x 1014)
1.4
1.2 1
Av. Pulse current (mA) 40 20
Pulse duration (ms)
0.57
1.9
0.4
Bunch frequency (MHz)
352.2
Physical length (m)
430
~460
535
3 different designs:
CDR2 (CERN ) based on 700 MHz high-gradient cavities
“LPSPL” for LHC (2007) with low beam power, for the needs of the LHC
“SPL” at higher energy, for the needs of neutrino production and/or EURISOL
29 January 2008

16. (LP)SPL New Layout (CDR2, 2006)
Linac4 (160 MeV)
SC-linac (4/5 GeV)
3 MeV
50 MeV
102 MeV
180 MeV
643 MeV
4/5 GeV
H- source
RFQ
chopper
DTL
CCDTL
PIMS
β=0.65
β=1.0
352.2 MHz (~ 100 m)
704.4 MHz (~ 400 m)
New SPL Design (CDR2, CERN Yellow Report ):
Linac4 (extended to 180 MeV) + 2 superconducting sections based on 5-cell elliptical cavities at 704 MHz (INFN/CEA).
Long cryomodules (LHC/TESLA-like, 12-14m), 6-8 cav./module, cold quads in cryomodules
Overall length 430m (for 3.5 GeV, was 690m in previous version for 2.2 GeV)
Medium b
High b
Cavity b
0.65 1
R/Q (Ohm)
235
575
Aperture (mm) 85 90
Ep/Eacc
2.6
2.4
Eacc (MV/m) 19 25
29 January 2008

17. PS2: main characteristics
Injection energy kinetic (GeV)
4.0
1.4
Extraction energy kinetic (GeV)
~ 50
13/25
Circumference (m)
1346
628
Maximum intensity LHC (25ns) (p/b)
4.0 x 1011
1.7 x 1011
Maximum intensity for fixed target physics (p/p)
1.2 x 1014
3.3 x 1014
Maximum energy per beam pulse (kJ)
1000 70
Max ramp rate (T/s)
1.5
2.2
Repetition time at 50 GeV (s)
~ 2.5
1.2/2.4
Max. effective beam power (kW)
400 60
29 January 2008

18. ROADMAP
29 January 2008

19. Detailed drawings in progress
Linac4 project
Site approved.
Detailed drawings in progress
2007
® mid-2007
Optimization of the layout on the CERN site
Negotiation of detailed work packages with external partners
CERN Council decision on the « White paper »
July ® September 2007
Finalization of the design
Detailed Civil Engineering drawings
September ® December 2007
Project organization inside CERN
2008: official start of the Linac4 project in January
Project review
Start of Civil Engineering
Conclusion on allocation of work packages / distribution of « remaining » tasks inside CERN
Start of construction of Linac4 equipment
Mid-2011
Progressive beam commissioning of Linac4
Mid-2012
PSB stop for modification
PSB beam commissioning
Beginning 2013: PSB operational for physics with Linac4
Yes !
In place
Organised in January
mid-2008
mid-2008
mid-2008
29 January 2008

20. Preparation for the SLHC
® 2011 for LHC and SPS
Selection of the most promissing scenarios for the LHC upgrade
Experience with the LHC and its practical limitations…
Detailed technical design of the LHC upgrade
Detailed technical design of the SPS upgrade
Prototyping of critical components
Detailed estimates of the necessary resources
Negotiation with external contributors
® 2011 for the injectors of SPS
Optimization of the layout on the CERN site
Optimization of compatibility with other users (EURISOL, n’s, pbars, heavy ions…)
Detailed technical design
Detailed Civil Enginering drawings
® publication of Technical Design Reports with resources estimates
29 January 2008

21. Implementation of the LHC luminosity upgrade
2012 ® 2017 for LHC and SPS
Construction of components for the LHC and SPS upgrade
Progressive modification of the SPS (vacuum chamber treatment, impedance reduction etc.)
2012 ® 2017 for the injectors of SPS
Construction of LPSPL and PS2
Progressive beam commissioning of LPSPL
Beam commissioning of PS2
2017
Connection of PS2 to SPS & final modifications of the SPS (injection system etc.)
Beam commissioning of the SPS
Beam commissioning of the LHC
29 January 2008

22. CONCLUSION
29 January 2008

23. CERN is soon going to commission the largest and most sophisticated particle accelerator ever built. Such an installation must be fully exploited.
It is time to prepare for securing its operation, increasing the reliability of all the infrastructure for protons and ions.
It is time to develop solutions for pushing performance to the limit.
Linac4 is a first step towards the replacement of many of the “old” low and medium accelerators that have faithfully served physics during half a century!
Our duty is to do our best to provide HEP with accelerators having a potential of evolution similar to the machines they will replace.
Thank you for your help!
29 January 2008

24. REFERENCES
29 January 2008

25. (LP)SPL and PS2: benefits
Direct benefits of the LPSPL + PS2
Stop of PSB and PS:
End of recurrent problems (damaged magnets in the PS, etc.)
End of maintenance of equipment with multiple layers of modifications
End of operation of old accelerators at their maximum capability
Safer operation at higher proton flux (adequate shielding and collimation)
Higher performance:
Capability to deliver 2.2´ the ultimate beam for LHC to the SPS
=> potential to prepare the SPS for supplying the beam required for the SLHC,
Higher injection energy in the SPS + higher intensity and brightness
=> easier handling of high intensity. Potential to increase the intensity per pulse.
Benefits for users of the LPSPL and PS2
More than 50 % of the LPSPL pulses will be available (not needed by PS2)
=> New nuclear physics experiments – extension of ISOLDE (if no EURISOL)…
Upgraded characteristics of the PS2 beam wrt the PS (energy and flux)
Potential for a higher proton flux from the SPS
29 January 2008

26. (LP)SPL cavities: elliptical, 704 MHz
Elliptical cavities at b=0.5 (CEA, INFN) are giving promising results. Stiffened for pulse operation.
Length ~ 0.9m
Designed for 12 MV/m.
* Feed 4 to 6 cavities per klystron: use high power phase and amplitude modulators.
29 January 2008

27. (LP)SPL accelerating gradient
maximum surface fields for SPL cavities are based on measured cavity performance (CW operation),
surface fields: 50 MV/m and 100 mT are challenging but seem realistic for pulsed operation,
chosen gradients for β=0.65/1 >> 19/25 MV/m,
29 January 2008

28. (LP)SPL cryostats based on the TESLA/ILC approach,
long cryo-modules (11.45/14.26 m) with low static losses, low number of cold/warm transitions,
cold quadrupoles,
difficult to repair (e.g. when compared with SNS), but hopefully less leaks,
long time for development and prototype testing!!
29 January 2008

29. Vertical cross section L-L of SPL tunnel
29 January 2008